Core drill



Jan. 24, 1933. A E-AD 1,895,001

CORE DRILL Filed Sept. 19, 1930 2 Sheets-Sheet 1' INVENTOR.

Jan. 24; 1933. a. A. MACREADY CORE DRILL Filed Sept. 19, 1930 2Sheets-Sheet 2 I N VEN TOR. 2247 2. Cl.

Patented Jan. 24, 1933 PATENT OFFICE GEORGE A, MACREADY, OF LOS ANGELES,CALIFORNIA GORE DRILL Application filed. September 19, 1930. Serial No.482,925.

My invention relates to core drilling in wells and particularly tosecuring cores which can be oriented to determine the direction of dipof strata or faults.

Orientation of the core is done by orientation of a core receiving tubeeither by instruments on the core receiving tube or by surveying thetwist of the drill string as it is removed from the well, both of whichmethods can be accomplished by the apparatus disclosed in my applicationfor patent,

Serial Number 107,980 filed May 10, 1926 for Core drill and means forascertaining dip; and also in my two later applications Serial Number271.932 filed April 21, 1928 for Core drill with clock operated meansfor ascertaining dip and Serial Number 430,908 filed February 24:, 1930for Orientation core drill.

In the instant application for patent an improved core drill isdisclosed which is particularly adapted to shallow core drilling wherethe depth is so small that the drill pipe can be accurately surveyedfrom the 25 well and for wells in which the amount and direction ofdeviationof the well hole from vertical is already known or very small.

An object of my invention is a core drill in which the inner barrel isswiveled inside the outer barrel so that the core will not twist apartduring coring and in which the swivel is locked against rotationautomatically when the drill is lifted off bottom and suspended so thatthe position of the core relative to the drill stem will not shiftduring the process of surveying the drill stem from the well.

A further object is an identification index mark on the lower end of theinner barrel which is visible externally so that the inner barrel can betied to the datum direction as soon as it emerges from the well.

Another object of my invention is an inner core receiving tube or barrelwhich can be surveyed accurately from the well and in which the core isreadily accessible-without excessive handling and disconnections liableto confuse the orientation.

r Another object is a projectionon the extreme lower end of the innerbarrel to resist rotation of the barrel about the core, to mark the coreand to identify a side of the core.

Another object is a novel form of thrust bearing for the swivel which iseconomically constructed, very free of movement, requires no packingglands, and has ample circulation channels.

Another object is a simplified mud guard to prevent mud or clay chunkschoking the inner barrel to the exclusion of a perfect core.

Another object is a dbris screen over the lower end of the core drill toexclude coarse gritty dbris from the annular space between barrels andfrom the inner barrel during lowering into a well. This form isadaptable 55 to caving holes in which the cavings are gritty instead ofsticky. In some wells coarse grit en ering the drill string from belowtends to lodge between the swiveled barrels to lock them together: thescreen prevents this di'fficulty.

Another object is .a core drill having a swiveled inner barrel in whichthe residual torque of the drill pipe resulting from coring is releasedbefore breaking the core from the country rock. Goring is done with thedrill pipe in compression and torsion. When coring is completed and thefirst survey observations for orientation are recorded the drill piperotation is simply stopped without relieving the strain at the lower endso that the cutting edges arestill exerted against the unfinished bottomchip until the drill pipe is raised. When the drill pipe is raised thestrain is relieved by a twist of the drill pipe of unknown amount but ofsufficient magnitude to cause an inaccuracy of the orientation of a coreif the orientation is attempted with most forms of swivel barrel orother kind of core drills. In the specification it will be seen that Ieliminate this source of error. Of course where the recording is done byinstruments carried by the inner barrel the twist does not affect theaccuracy but some operators prefer to orient cores by surveying thedrill pipe and the instant application discloses a core drillparticularly adaptedto accurate results for their use.

Another object of my invention is a core drill having an outer barrelrotatable about n the inner barrel during coring, the inner barrelprojecting beyond the tubular portion of the outer barrel so that chipsshaved off the core by itare easily disposed of and so that the innerbarrel is visible for orientation purposes. I

Another object is a bladed cutter head having holes in the blades forattachment of a net to exclude debris from the core drill.

With the foregoing and other objects in view which will be made manifestin the following detailed description and especially pointed out in theappended claims, reference is had to the accompanying drawings forillnstrative embodiment of my invention, wherein:

Figure 1 is a longitudinal section of my core drill,

Figure 2 is a cross section at 2-2 on Figure 1,

Figure 3 is a cross section at 3-:3 on Figure 1,

Figure 4 is across section at 4l-4.on Figure 1,

Figure 5 is a cross section at 5-5 on Figure 1,

Figure 6 is a cross section at 66 on Figure 1,

Figure 7 is a cross section at 7 -7 on Figure 1,

Figure 8 is a. cross section at 8-8 on Figure 1, V

Figure 9 is a grapple for handling the inner barrel,

Figure 10 is an elevation of the lower end of my core drill without themud guard or screen,

Figure 11 is an elevation of the upper connection of the inner barrelshowing the outer barrel in section and with the thrust spider removed,

Figure 12 is a longitudinal section of the lower end of the form of coredrill sh own in my co-pending application Serial Number 107.980previously mentioned.

Figure 13 is a side elevation of the lower end of my core drill with thenet for excluding dbris attached thereto.

Figure 14 is an elevation of the bottom end of the assembly shown inFigure 13, and

Figure 15 is a flat view of the net screen for excluding dbris as itappears spread out Similar numerals refer to similar parts throughoutthe several views.

In the accompanying drawings the principal members of my rotary coredrill are the inner core receiving barrel 1 swiveled within the outerbarrel 2.

An inner shoe or nose 3 is attached to the lower end of the innerbarrel. This shoe is of cylindrical external cross section except for alongitudinal identification mark or scratch 4. The inner cross sectionshown is nearly circular except for the longitudinal rib 5 althoughseveral other forms of internal cross section have been used. The lowerend of the nose is beveled outwardly and upwardly from an annuar cuttingedge 6. The bore may be tapered or choked at the lower end to lessenfriction of the incoming core. A core gripper maybe attached to oradjacent the nose to suit the character of formation. In the form shown,springs or barbs 7 riveted to the upper lip 8 project inwardly andresist escape of the core but are flexible enough to be pushed aside bythe incoming core. For many formations a simple shoulder is an efficientcatcher.

A combination thrust and check valve body member 9 is attached to theupper end of the inner barrel 1 as by screw threads 10. Washers or shims11 of chosen length may be used for adjusting the length of the innerassembly. The member 9 is preferably a casting although it may bemachined. The lower end is provided with a cross passage 12 and alongitudinal passage 13 forming a cage for the valve ball or closure 14.The

ball may seat on a seat 15 retained by a tubular screw threaded follower16. The follower 16 may have side holes 17 to allow escape of fluid inthe event of the mud guard l5 choking the end passage. The upper portionof member 9 is of reduced diameter to allow circulation between it andthe internal upset'of the outer barrel. The extreme end of member 9 isrounded to form a round head 18 functioning as a thrust bearing. A notch19 is provided for engagement with a grapple for lifting the innerassembly out of the outer barrel or a hole 38 may be provided to receivea hook for the same purpose. Transversely projecting fins 20 are on theexternal surface of member 9 just below head 18. The fins 20 extend to agreater external diameter than the external diameter of inner barrel 1and are provided with a downwardly facing surface 21 which is providedwith radial notches 22 for a purpose hereinafter described.

A sub or coupling 23 is attached to the lower end of outer barrel 2 tosubstitute more substantial threads for the soft conventional pipethreads. To provide large circulation space the upset of the pipe 2 isremoved, this not being necessary near the base of the drill column. Acutter head 24 is attached to sub 23. The cutter head shown is providedwith tour cutter blades 25 each cutting the same gauge externally andinternally and projecting a short distance ahead of the hollow portionof the head 24. The internal gauge shouldbe slightly greater than theexternal diameter of the inner barrel so that the inner barrel canproject through. The outer-gauge can be any desired andblades ofdifferent gauge and length can be used. The head is threaded internallyto fit sub 23 and the middle portion is provided with internal ribs 26to center the head about the inner barrel during rotation.

At the upper end of the outer barrel 2 the internal upset 27 is retainedfor strength and a tool joint box coupling 28 attached by screw threadsor Welding. The barrel 2 can be a length. of A. P. 1.. (AmericanPetroleum Institute) standard rotary drill pipe and in some sizes thecoupling 28 can be-the regular A. P. I. standard size although usually afew slight difl'erences in dimen-.

sions are desirable. The bore of box coupling 28 should be appreciablygreater than the internal diameter of the upset 27. The upper end ofcoupling 28 is threaded internally to receive a tool joint pin 29 and insome sizes this pin can be the regular A. P. 1. standard which resultsin a saving of special connections and resultant economy andsimplification of equipment.

The thrust spider 30 is preferably a bronze castin and consists of acentral core or body 31 flan {ed by ribs or fins 32 which extendlongitudinally beyond the core to form a socket in each end. The ends ofcore 31 can be concave as at 33 to form a socket to co-operate withthrust head 18 and the radius of curvature may be slightly larger thanthat or head 18 so that the bearing is at the 'center spot. Both ends ofthe spider can be interchangeable. Spidersot different length can beselected from instead of using the shim 11 to adjust the lengths ofinner and outer barrels. Small holes 34 drilled through the fins 32 canbe provided to receive a hook for lifting the spider out of the coupling28.

The conventional upset of drill pipe usually tapers both ways from themaximum thickness of metal. A thimble or bushing 35 inserted inside thetapered end and held against rotation by a set screw 36 provides acylindrical inner wall and a full width shoulder at the upper end of thedrill pipe piece. The upper end of this bushing may be provided withnotches 37 of a size suitable to co-operate with ,the notches 22 ofmember 9. The

' integral with coupling 28, or a bushing inside coupling 28. When thecore drill is suspended from the drill pipe stringathe inner barrelorganization is supported by the fins 20 hanging 'on'bushing 35 and whenthus suspended the notches 37 mesh in notches 22 and lock both barrelsagainst rotation relative to each other. p y i- Figure 12 illustrates aform of identification mark shown in my co-pending application SerialNumber 107 .980 and consists of a screw 47 projecting through the wallof inner barrel 48 so that point of the screw isvisible on the insideand the slotted head &9 visible from the outside. The cutter head of theouter barrel which revolves about the inner barrel includes blades 50projecting below a cylindrical hollow portion 51. The screw 47 and edge52 of the lnner barrel a re visible between the blades below the centralhollow portion of the cutter head.

A grapple is shown in Figure 9 for use in assembling and removing theinner barrel consisting of a body portion 39 having an eye 40 and springprongs 41 urging outwardly with hooks 42 at their ends. The sleeve 43draws the prongs together over the head 18 and is held by a removablepin 44. Instead of this grapple a chain or cable loop around recess 19,a hook inserted into holes 38 or other means can be used.

During lowering into a well, mud including chunks of cavings scrapedfrom the wall of the well is pushed ahead of the core drill and is drawninto the drill by rush of liquid filling the drill pipe from below.Large chunks cause trouble by plugging the core barrel to exclude core.To avoid this difficulty a mud guard of very simple form is providedconsisting of a single stick of wood 45 to which downwardlypointing'spring barbs 46 are tacked. The wood piece is ta-. pered sothat the small end having the barbs can be inserted into the bore of thebarrel leaving the large end projecting. The barbs book over the coregrlpper to support'the guard and the large end is of greater diameterthan the bore of the barrel so that it cannot enter until cut oil by thesharp edge of the inner barrel nose 3. As shown in Figure 8 the wood ispreferably of rectangular section so that a passage is left around it toadmit liquid without chunks to fill the drill pipe. v Other forms ofmudguards have been disclosed in my applications Serial Number 346,955filed March 14. 1929, and Serial Number 430,908. filed February 24,1930. Heavy wood, either natural or weighted is preferred so that theguard will ride lightly (in the top of the core but not fioat abovethecore.

The mud guard above described, is best suited where the cavings in thewell are of clayey character. Chunks of clay can efiectually block thebarrel against incoming core by lodging in the'check valve but'the clayplug. However, when the hard pebblesget into the space between thebagrels they are not crushable and only a few of the larger.

locking action is undesirable in the swivel type of core drill and mayspoil the core for urposes of orientation. The above remar s emphasizethe different effects between clay and gritty cavings on a core drill.

For gritty cavings a screen made of fishnet material fastened over theentire cutter head is useful and effective. Figure 15 illustrates a netopened out flat consisting of a fabric net 58 with say quarter inchspaces between strands and cut in a clover leaf shape. Edges can bereinforced asat 59 and strings or wires 60 provided for tying to thehead as illustrated in Figures 13 and 14. When this form is used theedge of the inner barrel pinches it in two cutting out the cen tralportion as fan as slots 61 which allows the outer portions to float awayfrom the circulation outlets. Instead of tying around the cutter head atthe top of the blades as illustrated the net can be wired to holes 62drilled through each blade below the cylindrical portion of the cutterhead where there is less danger of the net being scraped off by the wellwall during descent.

My core drill is assembled as follows: The outer organization of cutterhead 24, sub 23, outer barrel 2 and tool joint coupling 28 is supportedin the rotary table on slips.

The inner organization of core receiving tube 1, inner shoe 3, andthrust-check member 9 is picked up by a chain, grapple or hook in recess19 or hole 38 and lowered into the outer organization. The thrust spider30 is set on top of head 18, the drill pipe connected by tool joint 29,and the core drill raised for inspection of the lower end. The mud guardor fish net is then attached and th drill lowered into the well. Theoperation of my core drill is as follows: During lowering into the wellthe interior organization is supported with the notches 22 meshing innotches 37 so that inner and outer barrels are locked against rotationrelative to each other. -When the core drill approaches the bottom ofthe well the lower end of niud guard 45 (or 58) touches bottom first andstops. The sharp edge 6 ofthe inner'barrel imposed on the wood withweight shaves oil the corners of the stick so that part of thestick canenter the barrel and the shaved off corners escape to the circulation.The stick is now free to lead the core into the inner barrel.

The nose 3 of the inner barrel next touches bottom and the outer barrelfollows rotating to dig core. It will be observed that the core dug bythe rotary cutters is of larger diameter than the diameter of the innerbarrel. The result is that the nose of the inner barrel rests on the topof the core and notches 22 lag behind notches 37 unlocking the barrelsto permit the outer barrel to rotate about the inner barrel. The outercutter head rotates to dig additional core and as it descends the Weightfrom the drill pipe is applied through spider to head 18 to force, theinner barrel longitudinally over the core. Ordinarily'the lengths areadjusted so that the edge 6 of nose 3 during coring is a fraction of aninch above the edges of cutter head 24, except in very soft formationswhere the weight of the inner member sinks theedge 6 by gravity ahead ofthe cutter head 24. With this adjustment the shavings cut by nose edge 6from the core have a free lateral face to break or shear from and escapedirectly into the circulation below the tubular part of the outer barrelso that they cannot accumulate between the barrels to lock' themtogether. Furthermore the unshaved portion of the core protects theinner portion finally recovered from erosion by circulation fluid. Thespider 30 rotates on round head 18 as a bearing and this form of bearinghas proven very free and practical for operation in muddy slush.

Circulation fluid or slush is pumped down through the drill pipeentering the core drill from passage 53 and passes through centralpassage 54 of the spider, passages 55 between the fins of the spider,down the annular passage 56 between outer and inner barrels,

but close enough to the shavings to carry them away in the current andthat the cutting edges are readily and efliciently cooled; Liqu'id inthe inner barrel displaced by the incoming core is vented to the spacebetween barrels, 56.

It'will be readily seen that this core drill hasmany advantages.

When coring-is completed and it is desired .to orient the core bysurveying the drill pipe the rotary table is stopped. The cutters thenrest on bottom 'with residual torque of the drill pipe pushing slightlyagainst the unfinished bottom chip and held against it by torsionalfriction of the drill pipe against the well wall. Observation is-takenof the tpp of the drill pipe. The core drillis then pulled up by pullingthe drill pipe. The first move lifts the outer cutter head-clear of'the.nnfinished chip'and relieves the bottoinresistance to torque and thetorsional friction on the well wall. with the result that the drill piperesumes its normal untwisted state by a slight twist at the lower end,the upper end being held by the elevators. In a long string but may beconsiderable and even as much as v a complete revolution. In my coredrill,

with usual adjustments the outer barrel must be raised an inch or morebefore it picks up the inner barrel and it raised slowly the torquetwist is relieved before the inner barrel and core are picked up. Myconstruction eliminating the torque twist removes one of the greatestinaccuracies of orienting cores by surveying the drill pipe.

Fins 20 are engaged by thimble 35 or equivalent to support the weight ofthe inner barrel during raising to the surface. Ngtches 22 and 37 engageso that during raising the inner and outer barrels are locked againstrelative rotation. In contrast to my construction in most other forms ofswivel barrel core drills the barrels are free to swivel while suspendedso that vibration during raising can cause their relative positions toshift and spoil the accuracy of the orientation record. With modernrotary equipment usi'nghigh speed cables and reels great vibration istransmitted to the drill pipe when raising. With ;my form the weight ofthe loaded inner barrel holds notches 22 and 37 positively engaged toprevent rotational shift during raising and thus eliminates anothercommon inaccuracy in orienting cores. When the lower end of the coredrill emerges from the well the lower end of the inner shoe 3 is visiblebetween the blades of the cutter head and the position of theidentification mark 4 can be observed for orientation. In case the markis not in a convenient position an additional and diiierently distinctidentification mark can be placed on the shoe for record, as by a punchmark. 1

The inner barrel is then remov d from the outer barrel and the coreextracted- By of the drill pipe torque before liftin the core' ofi'bottom: An identification mar on the inner barrel visible below theouter barrel: Free circulation passages: a large core cut by the rotarycutters which is not so liable to injury from circulation erosion:Provision for immediately removing shavings cut from the core by theinner barrel before they can get between the barrels: And a niud guardto eliminate clogging of the drill by .cavings.

I claim as my invention: 1. A core drill for orienting cores compris ingan outer barrel a rotary core cutting shoe on the lower end 0 saidbarrel, an inner core receiving tube within said outer barrel, saidbarrels being rotatable relative to each other when supported from thebottom and locked against relative rotation when suspended from drillpipe.

2. A core drill for orienting cores comprising an outer barrel, a rotarycore cutter 3.. A core drill for orienting cores compris ing an outerbarrel, a rotary core cutter on the lower-end of said outer barrel, aninner barrel within said outer barrel having a limitedlongitudinalmovement relative to said outer barrel, anda projection on said innerbarrel adapted to engage said outer barrel to suspend said inner barrelthereby, said outer barrel beinglocked against rotation about saidinner-"barrel when said inner barrel is suspended therein and free torotate thereabout when the weight of said inner barrel is not supportedby said outer barrel.

,4. A core drill comprising an outer barrel having cutters on the lowerend thereof and an inner barrelhaving an annular cutting edge on thelower end thereof, a rounded head on the upper end of the inner barrel,a spider having a central body flanked by lateral fins slidable withinthe upper end ofsaid outer barrel to engage said-head, and a topconnection for the outer barrel to lock said spider between said headand said connection to form a thrust bearing, said fins extending beyondthe central portion to form a socket "at one end within which said headcan revolve against the end of said central body portion.

5. A core drill comprising an outer barrel havin cutters on the'lowerend thereof, an inner arrel having an annular cutting edge on the lowerend thereof, a blunt head on the upper end of the inner barrel, a topconnection on said outer barrel, and a spider slidably disposed within'the outer barrel between said head and said connection to form a thrustbearing, said spider having a central body portion flanked by lateralfins extending beyond the ends of said body portion to form a socketwithin which said blunt head can revolve against the end of said centralbody-portion.

'6. A core drill comprising an inner barrel, an outer barrel rotatablerelative to said inner barrel,-a headon said inner barrel provided witha convex end, and a socket member within said outer barrel including acentral body having a concave facefacing said convex end andlongitudinal ribs extending laterallyfro m said body to -the wall ofsaid outer barrel to form longitudinal cir-' culation passagestherebetween, said ribs extending beyond the concave end of said bodyand beside said head, and said socket member being longitudinallymovable in said outer barrel to follow down against said head.

7. A core drill comprising an inner barrel, an outer barrel rotatablerelative to said inner barrel, an extension on the upper end of saidinner barrel provided with a blunt head, a socket member Within saidouter barrel 10 having a central body portion flanked by longitudinalribs extending longitudinally' beyond said body portion, said ribs andbody portion forming a socket rotatable about said headand adapted toreceive longitudinal thrust from said head,

the spaces between said ribs forming circulation passages, and saidsocket member being longitudinally movable in said outer barrel tofollow down against said head. v

In testimony whereof I have signed my name to this specification.

' GEORGE A. MACREADY.

Yes

